The present invention is a system and method for determining the point at which a cutting tool on a Computer numeric controlled machining system has reached the end of its useful life, then automatically replace said tool, utilizing a computer algorithm with user definable parameters, in conjunction with an automatic tool changing system.
The condition of a cutting tool is critical to any type of machining operation. Tools that become worn through excessive use can have a negative effect on both the quality and the accuracy of a machining operation. Excessively worn tools may also contribute to collateral problems, such as the premature failure of bearings in routing or milling spindles, or tool breakage. Tools that break due to excessive cutting force, may also result in serious personal injury to operators or others who may work in close proximity to the machining operation.
A problem of the machining industry is the lack of an effective system for automatically monitoring and managing cutting tools during the course of a machining operation. Prior art addresses this problem by utilizing a number of methods, such as monitoring the electrical current of the cutting spindle motor, calculating the total amount of time that a tool has been in use, or the total length that a tool has traveled during the cutting operation. Each of the aforesaid methods has some value in determining the useful lifecycle of a cutting tool, but each takes into account only a single, quantitative factor. They therefore fall short of the principle goal of utilizing each tool through its maximum useful life span under a variety of different conditions, regardless of the many factors contributing to machining tool wears.
To effectively predict the life of cutting tools for a CNC machining center, several factors must be taken into account, including feed speed, the speed at which a tool is fed through a cut; peripheral speed, the surface speed of the outermost diameter of the tool; and tooth/knife progression, the distance that a knife or tooth progresses through the material per revolution of the cutter. The type of material that is being cut is another extremely important factor.
Peripheral speed is a direct function of feed speed, and together, they are part of a simple mathematical equation used for calculating tooth/knife progression. The optimum feed speed is therefore a stable characteristic of each individual cutter, having been determined in advance by simple mathematical calculations. Conversely, the type of material being cut is a variable; therefore no single quantitative factor can be applied.
Taking into account all of the above named factors, it is possible to accurately predict the lifecycle of a tool. However, in doing so, the operator of the machinery becomes burdened with the task of manually tracking the actual time that a tool is engaged in a cutting operation and differentiating the variables associated with numerous types of materials. In mass production situations, it is unrealistic to assume that this could be carried out with an acceptable degree of effectiveness.
The first object is to effectively monitor and manage the use of cutting tools in a CNC machining system, based on a number of variables, utilizing computerized automation.
A further object is to achieve the first objective with minimal operator intervention.